There are ongoing and increasing demands for weight reduction in motor vehicles. One area of focus in this regard is the frame and overall structure of the vehicle. For example, it may be feasible to redesign certain elements of the vehicle structure so that these elements can be fabricated from relatively lighter materials (such as polymers or aluminum) instead of steel. However, certain elements of the vehicle must also have sufficient strength to satisfy collision test requirements.
One example of such an element is a side intrusion door beam incorporated into the structure of a vehicle door. Such beams must be strong and stiff enough to resist deformation due to a side impact, long enough for a side airbag to properly deploy between the door trim and a passenger seated next to the door. For this purpose, side door beams are formed from high-strength materials such as boron steel. In an effort to reduce overall vehicle weight, extruded aluminum tubes have been considered for use as door beams. However, extrusion grade aluminum alloys such as 6082 or 6061 have much lower moduli of elasticity and much lower strengths than boron steel for a given beam design. If the beam re-designed to provide the necessary strength and stiffness using an aluminum alloy, virtually no weight savings are realized from use of the aluminum alloy. In some instances, the weight of an aluminum door beam may actually be greater than the weight of a boron steel beam having equivalent performance.
Thus, a need exists for beam structures and other load bearing structures which meet performance requirements and which have lower weights than existing structures.